Process of lithograining metal plates.



P. NIEMEYER'. L PROCESS OF LITHOGRAINING METAL PLATES. APPLIATION FILED FEB.24,1912,

15,045,068, Patented NOV.`19, 1912.

Cri

To all wmm 'magi concern.:

` Timiiiri Hobgln? in im: mi: Smile of New Jeisey, have invented ceiizun -iiew ami useful lmpiovunwns in liiwcesSeS sist if the solid meal fie@ Q coming sub# 'stances or nclhzien Salis, uml shall be 01' a chaactei' i0 tali@ and pi'ply hield the Suh- Stamce. Whil@ resisting he fmce. of lha arisfs pencil when the plais. lwug prepayed for use by Such niehod, and :i150 lo ie- `the equirerd ammini. of Water, mf moist fe.)

ceive the figures of outlines when' applied thereto by ih@ usual ransfes: ixielwcl': and. i0 furnish such n giziinefl plae which Shall have iis inteisticefs, or the spaces bwcen such elevaions, of a gieph nml charm-.ier proper'imd elecive G 'taking mi@ h'ohiing holding areas, 'While lie plaie is in usa @ii a lifhographic priniiig-prlss.

ln the accompanying mwing illus i. ai: my present improvemeis in lihngiz p i printing;-rplates,-l*`igure i is; a Secioiial Sid View of a receincla with a plate iheieiii' for: irenmeni; wliih suhmm j il in a bziih of h@ characer hel'eiiiaft'e (h. @cibi-.51. ligj. "2 :L similm' View showing lha rewcpuclc in :i cl'mi'iged pnsiliU-ii. il being tillgml {Ov-:nm

wha-wiwi.' i0 subject i'he/sifsice of ih@ plaie/ im u lively forcible washing achim. Fig. I)

lm' to n portion of Fig. l bui greatly enlarged, for illustrating the' following description i'egmfling' lie ilcp0siioii of granules hy {lv/intimi and gravity. Fig. i is a View" Similni' to U3 but iiiiich mora enhuged 'for illusiatiig- Qeituiiz pavilion@ of the following clesciiption and explanations; is a vView supplemeiial to Fig. 4. Similar characieis (.Qsigiia like parts in allhe views.

ulivi'. i.-

in pri-paling 'm zi plaie hy my procl 'plm-Ce the l laie, as F, ui Sonia suitable wfwplzich.. C o" depfh i0 hohl he bath '.lhe Size :incl pmpoi'inns of ih@ receptaclw fr? lha' ordinary fluid acid of cmnmei'ce .im

desiieil inequalities oi" suffixe@ ancl s0 ha add, t@ che bath n quannin, i

"me ,:aiicles' adapted i0 De ienaiilj.' FWF/'iight i@ *fioiziicgn and hiivlng an avid-Te. Sinni. qiiiliy. and haviiigsuch ansple 4cifc ,gravity i0 with@ 0i: dogmsil on theplni-e lmi :um prwgfx'ffssivcmanner. s@ that she wiiiizlnio nu ho plate in n (my zmiljf l m' depth during' hc? :icimi nf die: fwiil mi smal plate. Thug i pluie is; Cmimiri'mi'ly suihjvciefjl to ielliwii hy ih@ :icifl and a iiioflil'icf coi "isxh i :i (lopssiiiion mi sclimnulaiion of a fio/tm im nizilciiiil amu'mulal'ing lheieon during the zisiinu m' ih@ acid. in practie, I pref?? granules having a Specific g'aj'ity 0i hemugcn (me und (me-half'and two and' o half times thai of Wae, depending some; what @il thi? ess and shapes of the ,q'ziii uhm and somewhat, als, on he acidity c.. ih@ lilith.

'The otaioii f the granules is iiicnl at l Eiga l. and :2, Whey@ the Smfili gm;

or floaiiion; and in practice man.; @if fthe' so ianmin, piacjfcicaly ciiiiiiouslg, but t er to keep he balli ".f of seflimen'ration mat-'arial in the form has, li find, slight it any disadvantage. On the. bath E standing still :tor even. a brietm time, many of the granule. ,t become deposited by' gravity into a relatively evenly spread. layer upon the plate-surface S, ap proxiniately indicated 'ton instance at g, Figs. 3 and Il; and, by rezfisou, :is l suppose, olf the cheulical and volt-aio or other qualities of the materials, and of the conditions thus established, the surface S is at once subl jected to a reducing action ot' auch a char-- acter as to tend to form a grain therein ot the quality and water-retaining capacity quired in the lithoffraphic art.

When the plate ie in the acidulated bath and at a suitable distance.y below the surface thereof, the granules continue accumulating on the plate Vwhile the acid is eating away the surface ot the'inetal. The greater the depth ot the bath over the plate, the greater will be the amount of that accumulation, or deposition (hiring a given time and. from a given initial proportion or quantity of the. granules in the Huid. Therefore by suitably regulating those proportionate amounts and the 'depth of the fluid, the rapidity oit the granule-deposition may be controlled within proper limits, which practice are ascertainable by trial and ob-A servation ot the amounts of surface reduction in given times, for the production such a coarseness and depth of the grain as may be desired.

ylllhen the reducing action proceeds tor a, short time certain dissociations appear to laire place, Awith the formation of salts which by their position on the plate-surface tend to reduce and suspend the chemicalv or metal-- reducing action, and therefore l subject the plate at intervals to a 'washing or clearing operation which, may be performed by lowf ing the bath over the surface with sufficient force for thereby dislodglng such accumu lations or depoSitsV-if any there may be produced-and then agaln cover the plate.

by the deposition of the granules thereon by gravity, when the reduction process goes on again; these successive steps or stages are repeated to the extent required for lbringing the grain up to the desired depth and formation. At each successive re-dep0- sition lot' the granules, the undulations then already 'produced tend to modify, as I apprehend, `the manner such new deposi tion, so that the metal is removed by successive stages in which. any particular small area, or given area,-such for instance as one of a size less than that of a. granule,-- is deepened little by little, while at each successive stake 'such obstructive salts may have been 'termed on the surface, S, are cleared' ed by the washing operation.

The acid begins acting upon the metal'` over nearly the whole surface, and it :ip-- pears to be probable 'that the metal-reducing cxplaimtions.

minces action `is in some fa y progressivelyv modified as to the distrilmtion ci the 'points of relatively greater and lesser elifeet, during the progress ot the deposition which accumulates upon the plate. When by the agitation of the bath, however performed, the flotation ol the granules is accomilished, the acid will, ot' cotu'se, act about equally over the entire surface oit the metal, and will, as l suppose, become Yvariable or irregular during the innnediately subsequent and gradual. re-dep iition by gravity of the flotation mater.' l. By repeating the flotation at :frequent intervals while continuing the plate in the bath.j the metal subjected to suer ssive treatments which in one respect are each ot a similarly varying or progressivo character, since during each said treatment the restriction of the metalli-educing action goes on progressively from a beginning at which this action extends over the whole, or nearly the whole, surface and is thereafter progr ivcly reduced toi/ard or nearly to the point of cessation.

ln pra ntice it will usually be sullicient to carry this progre. reduction only to a point where therJ a substantial lesseniug oit the nietal redi 1g action, and then clear off the accunir ion on the plate of the lotationunaterial and also at the same time clear oli such prodmts as may have. been. termed` by the action of the acidbath and the metal removed thereby from the plate. This step being performed, :including the re-iotation ot' the granular material, the redcposition again begins and goes on as before, for subjecting the partially grained surface to a further stage of reduction; and so on, unt-il the depth and character of grain is obtained, as may be required. I

When the surface S has been reduced to a partie.lly-fo1'nie :l grain, and the surface is cleared of such obstruct-ive salts, aqueous or otherwise, as may have been formed between the metal of the plate and a metal of the granules, it is evident that on a re--deposition on the plateiof the said granules, these will normally deposit or form the lower series or layer, g, Fig. 5, in an undulating arrange ment or formation, so that the specific relations of those `metal elements to the grain of the plate will naturally btmoditicd at cach successive re-deposition stage of the process. .This feature will be understood by com )an V ing Figs. l and 5, in View of the preceding The plate, P with its partially grained surface S shown with granules, g, re-deposited thereon in an un dulating and irregular arrangement,` such as naturally' would be caused by the process above set forth, when the granules fall by a slow and gentle action through a. fiu'ul upon an undulating surface. Each stage ci". the proceus, ther' re, is not merely a repetition ci the tiret, or :it a next ].reced lac ,since eachsuccessive re-r eoositioe is mani on a more advanced formation oit the surface of the plate.

As suitable fiotationmiaierial, pre' ably employ some metalio salt wie li met materially reduced or eieeierl by'tieaeidbatlnja'hen this is of the moderate degree 1 lL metals, ami preferably of two and copper which, beceuee o strength .or acidity which is sufficient for slowly eating awal the metal six. j aiil Whieli, at the seme time uae aI {Sreferably of a 'fieke-like the granules 'of a size euitao ness of grain desired, amil ofi e .epeei of this material in the batir 011e kind of granule or l'lotati material which I emaploy, more especially for t 1ting eine platee, is e compound materiel Coinpounc'lecl preferably of the salts of me other than Zinc; and Siberi-lian the metal of A plate, when this .is not of ziio, @ne sue-li material ie e, com ounci formed from -i en an 'SLAJ anfe to the acid of the bath anni tie Small size and low weight oi its greiiulee7 pro (luces by tlotation and gravity a iieposi tioii of goed qualityl and eiieet. Foi' Acompound prefer one of the formula sary at this time to 'fully set J1for-li anfl FeCy+2CuCy This material a'opeiv's lie particularly' 'suitable because of qualities above mentieiiefl, and elee, ae apprehend, because of its ee'ct on, er the part it takes in certain reactions9 which it appears may takel place during or incident to the metal-reducing action upon the plate while in the bath mlVliile l am mueble and deem it unnecesplaiu the epeeio phenomena which esidently or probably occur in the solution, e1""frfor instance as the ioiizationrand 'the voltaiv action, or ,sueli 'others may 'take place' l. apprehend 'that in some manner the granules of the copper and iron Sal ate to modify the'ehemieal and ele u actions and reeetioiis upon the zine and to relatively localize or accentuate the metal reducing-action upon a great number ot'l minute. areas, and thus regulate oi' control the reduction of tlie plate-Surface to the ilesired grain-ormatien; anal, i apprehend tliiS may be clue te sumo intimate eotmeetien lietive'en chemical fluctivity, .since the acid, espe acidiemployefl as eleetrolappears to have the proper .eed e relai high, electriealeonduotii' y. @ne tion as to ,the way these reducirU may perhaps be reglilate-, 'e inclined ii: Fig. 3, where a layer of eetaleelt granules, g, lie close tothe sursaee Sg vinile activity and eleetrica'l' een-v elec e7 some liiifl enel the spaces z/ nel so in eo e i unequal amount' o' rlistibiiti actie on the suvi the ple y e way displace the tim' this more s mee xiiaue eiea so eoerefl ley lle geanule., which may be eaicl te' form an obstacle efe teli aga' t the ee approa of ile eei the greuulee peate in several respects jeeally mylien i irmef of a stili mor se, when :orme

may or capaci' double sa ei aoiiole meenariieall second, chemically, and aleomest probablyJ phenomena mw 'e eubsta ee, liu'.

granules comeompouiicle or designare@ es preferably employ time'iron-oyanogen ami,

@opp N ruegen salle, respectively, ande these lrefer to employ the cyauatesyaiicl the copper-salt or oyimate in excess of the iro' salt or eyanate. ltliougli Zinc is elaeserl as a (iivaleutmeial. it ap" Some cases to be able in reactions iaolving a pluality of other metals? to replace seme @they (lii'alcmt metals, i 11Kling i perliapf. coppia-7 if iieli if e zie. mouoi'aleit aetl iiyaleut in sueli ring i111 my proc Some' lie phenomena of oecur, Also; .it y the osmotic aetei or pressure or the electro-osmotic value in solutions, iron is classed as having a negative electromotive torce, Whereas, in comparison, both zinc and copper are classed as haring a positive electrolytic, or electroosniotic quality or value. Thus in treating zinc plates with a flotation-material having a salt of iron and a salt of a more positive metal, (such as copper for instance), the granules are composed in part oit the salt of a metal which is7 as regards its electroosmotic character, negative relatively to the zinc and also relatively to the metal of the other salt of the compound of which the granules are-formed i When the gravitating granules are coinposed oit a. compound oit' cyanogen salts of iron and copper7 and Whenthe iron-cyanogen salt is a cyanate, that compound will th Y@etere comprise two metal-cyanogen salts of which one is the cyanate of .a divalent metal (iron) having an electro-osmotic value relatively negatire to the zinc and also to the metal (copper) of the other metalcyanogen salt (living to their low specific gravity and their size and character, this kind ot' granules are readily tiotable by agitation ot' the bath, and `are deposited therefrom onto the plate surface in a slow and regular manner particularly favorable for the requirements of this method of making the litho-grain.

In this process, the 'object is to reduce the original plane vsurface to a grain-surface, rather than to supply such grain as an addition to` the plate. In View of this purpose, and also for convenience, I designate the process as one tor litho-graining metalplates, thus referring to the adaptability of the plates when so grained for use in the art oit lithographie printing.

While a grannle of the double cyanate restson the eine surface, the molecule of iron-cyanate may be considered as being held in place by its association with the molecule Vof copper-cyanate, and thus may 'part with some ot its cyanogen directly to the zinc, which has a strong allinity therefor; and such an exchange may, I infer, be aided by the oxygen supplied by the nitric acid to the iron -as well in. 'mrt to the Y zinc; and7 owing to the minutenessbf the granule, that exchange or recation may therefore take place, as to each such granule only in a correspondingly minute area'7 with the result of forming a great number of closely arranged but distinct lpoints of reduction' on the zinc surface.`

I'Vhen a, suiiciently dilute acid bath is used, the metallates, particularly zinc plates, may be su )jected to a primary rc1 lduction which is initially distributed. over the Whole surface and is then gradually restricted bottias to the distribution and the regularity of the reduction7 this bein accomplished by a progressive gravitational deposition of an acid-resistant flotationmaterial; and, next, subjected to a second reduction by repeating the said operation on the primarily-reduced plate-surface; and then subjected to a. further reduction 'by repetitions of the said operation on the secondarily-reduced plate surface, whereby the final surface is obtained by three or more successive reductions, each of which begins with the plate-surface at adifferent stage of grain-fomiation.

In litho-graining metal-plates in the foregoing manner, the grain is developed or produced in a clean and eti'ective condition, being formed or composed of' the solid metal and free of adherent films, deposits or coatings, and Without the formation of substantial salts or the like to impair the quality ot the surface-grain for use in lithographie printing. On zinc plates. the process may be properly carried out in from three to eight minutes, depending on the strength of the acid, the depth of the bath over the plate, the quantity of the tlotation-material in the bath, and the frequency of thc re-flotation and rc-deposition ot the granules of that material. In practice I prefer to so regulate those periods and quantities as to provide for from three to six of the said iedepositions during the complete operation.

In applying my present process to the graining of plates of metals other than zinc` such an aluminum or copper, either pure or alloyed, other dilute acids, instead of the nitric acid7 may be used, preferably selecting such a kind and degree of dilution of the acid as will act slowly on the metal-surface, andthns give time for the desired number ot ,re-depositions of the flotation material during thc process. In some instances such other acids may be used in graining the zinc plates, especially when the compounds or salts, Whether cyanates or not, of which the granules aromposed, shall be of a characier to Work in harmony with the particular kind oil acid employed and not be rapidly consumed or neutralized in the bath.

Having thus described my invention, I claim:

l. The process of litho-graining metalplates, which consists in reducing the platesurface in an acid bath under an accumulating deposition` by gravity of granules which are floatable by agitation of the bath andlare resistant to the acid.

2. The process of litho-grainin Vmetalplates, which consists in reducing t 1e platesurface in an acid bath under an accumulating deposition from flotation of anules and continuing such reduction to tgl; point of formingn partial grain, next clearing olf the plate-surface and retloating the granules,

dion subjeoing ne plinio-s *face o' ini-- thai? roduion iii/Miei' 'acounuiziing ifedeposiioi of he giannies.

3. That inigoi'ofeinen in tho iii-; of iiiio gi'siiniiig moisi-sinks? which oonsiss in snojecting iii@ piste-swims in an acid iur-.h to al rimani] .duoioi initially disribus-(i over. Fn@ fhole'suraco ami Shen graduaiiy restricting thai distribution m15 'Che 2251iiaiity 'of iia '.dncion by tho grmfifLaionai deposition oif'an acid-resisian. iot

teriai and next subje'cting ik@ suriaoo io an mditional' z'ecinction by iepeaing he said operaions primary reduoion,

4. That iinpi'ovement in the ari; of iiiioraining metal-platos, which consisi's in subgecing the plate-Surface in an acid 'oath to a primary reduction inii'aiiy disiibnsd ove? the Whois surface and 'nen giadunily vz'eslfioiiig; hat distribution and the ragulaiy of diss i'educzi'ion by the giaviaionai deposition ol" an acid-resistant gisnuifi omtion'infiteriul, an@ nex subjecting he suz'face to successivo sddiionai zefuoions after suoli primary i'sdnorion, by suojfin this ')iae-sui'fac to renamed gra aionai dopositions of the ouon grannies Whiie continuing he acid treatment.

5. The process: oi itho-gi'ziining mamipintes. which consists in reducing the piatssnifacc in an acid bath fonaining in fioiation grayiming grannies of u donbie ssii of two diierent metnis, and con'innii'ig die acid treatment While acoumuiaing o. 33Mintionai deposition of such ioi'aion niseriai upon the platesui''uce.

The pocess of litho-graining nistai plates. which consists in reducing' fins piziesui-face in an acid bnh conmii'iing in fiomtion gravitziing granuiss of :1 donbls nii' of two diiei'ent ineals, and conii acid treatment during successivo @sin tional rie-depositions of such iotaiiz i nisferial.

T. The process of litho-gi'aining iiiecaiplates, which consists in inducing the nidi@- surface in an acid bath containinb in iomtion graviiaing granuiss of a d ubi@ sali of two dii'oi'ent n'ietais @they iban 'the nietai of the pluie, and continuing the :wid i'eatnient while zl'ccun'iuiating i gi-m'iaiionai deposition of such iioiition niaei'ii upon ih@ plate-surface.

S. The process of .Milo-grinning maialpia'es, whish consists Vin iediioing'me piatesurface in an acid baih conaining in {iotation gmvitating granules of n. double sait of two diii'eieni :nsais ohex hain 'the nieai of the. plae.' and confirming the ucii ti' anient (in'iug, succes. Te griwinio-nai depositions oi'f suoii ioa'ion mzzoiisi 9. The process of' iithograining nie-ini plates. which consists in reducing ho pini/esuifzice in an acid bath containing in fiom- 'upon 'die piae-suz'face.

s oiie' inin zho nieta] which is iront sind malignant n iis .fiooiunuv l Lg, -101ml deposition o: such oauon .iiiatoi'ial op-on the piae-suriaco- ,is p3? U.ss litho-gaining metalpiatos, which consists inrefiucingthe niais@- siuaco cil b-.ih containing .in 50mion gmviaiing grannies of a doubio'saix* two i'eren mesis oiez than the inem-1 o ichs pim@ ons). o e of which is iion, and 1 coiaining ibs mii; 'ea'men; airing sucoossivo graviiationa @depositions Off such ieation matosiai.

prooess 'of ii-i.ogfa.ia1ing @stab plums, which consisis in reducing the pister surface in in acid bailo conmining in fiom- !ion graviating granules oi :i double sait of iron and copper. and continuing io aoiii imminent Wiiiie acoumuiating Si Ta/iis.- tionzil deposiion o such iiioaiion maeai l2. The pronos oi' iithograining ,.ieal pistes, 'which cons ss .in reducing the niaisA siufa in nnncid bah containing inniosfion gmi'iiating grannies of a subie sait of iron and sono?, and conainingf the ascii osinent uilnf sucessive graviationiii re-deposiiois o such otiiiion mais-asiel.

1.3. The Lnocsss of iithosgminingnielai ich 'st in feduoing the.f phi-tobah Qonaining ifi i'ios," Lnies ill AJoubie,ssii of giviiaional mammal upon tw l. The proce o* iiho-giammg mear b mies, which coi n reducing the pienosn an baii oonalnng in iai'i'ulos i and having iis Coppariion-sait, anti. con s unioni aiming suooossivf: i'edeposiiions of such of iihogmining inail-ai inducing ih@ pigis- .zii bzfh Containing iii oal 5 grannies composed cyanues ivm iei'en mobils, and oontinuing :fici/[i imminent .Vhie acoumu iaing si gravi nai deposiion such ioaion inaeii: upm die piabosuifacs.

lo. The igioa oi! iiiio-giaining maiz-iipiaes. "vvi'iich'vons'ss in @firming the pimiesuface in an i. 'iah conaining in ioia ion gi'nviziing mui-fes con'iposeai of iie ojfanfivs of two Znzais, and coninning the acid isai'noni (hiring socessiw gi'avitnionzi ifs-deposiions of such fiom; ion mateiiai.

i?, The proosss of ihograinng ineala, wn. surface in plates which consists in reducing the, pintesurface in nn esiti oath containing in tinta tion gro i'itnt tion grnfritating grni'niles composed ot the cynnntes of two ditlercnt metals other tlm-n the inetnl ot the pitite, and continuing the :reid trcntnac while accumulating :1 gravitational deprenion oit sncli flotation materiel upon the plntewnxftnce.

ld The precoce ot litlio-grnining metalplntes, Woicli cons, in reducing the platesurface .in nn ncitl birth contnining in flotation grsrvitnting granules composed of the cynnntcs of two different metals other than the metal ot the pleite, :intl continuing the acid treatment during Successive 'evitationcl :te-depositions of such flotation materinl.

i9. The process ot lithogrnining metalpletes, which consii in' reducingr the plate in nn acid hath containing in flote.- tion grnvitatingg granules composed ot :1 compound metallic enit comprising an iron eynnogen snit, and continuing the froid trent nient t 'ig a grnvitn'tionol deposition oi': Such tlotntion me upon the pletc-snrfoce.

2t). The precoce of litho-grinning metal-- plates which concis-its in reducing the plateeinl'nce in :in ncid bath containing in tiotu tion Tramites composed oit n, compound -metnliic snit. comprising nn iron.-oynnogen salt, and continuing the acid treatment dur- Ing successive redepositions by gravity of such lotntion mate-rml.

2L The process ot litlio-grnining metalplates, which consists in reducing the VpleteH surface in on acid birth containing in tinta.- t-ion grmitnting gran'ulce composed of the cyenntee of two diil'erent motels other than the metal of the plete and one of which is iron, and continuing the acid treatment. while accumulating n gravitational deposid tion ot such flotation material upon the pinto-surface., r

he procesie ot lithograinin metalY platee, which consists in reducing t4 e plate-- surface in nn ncid bath containing in flotan nig granules colnpoeed of the cjlvenates ot two different metall; other than the metal ot the plete and one of which is iron, ond continuing the acid treatment during nucceesive gravitational rei-depositions ol such lotntion materiel,

The procese of lithogrnining metalpln n, r-flrich con' c in reducing the platesnr'nce in :in heid netti containing in flote tion grevitntinggrnnnlen composed of the cynnotef-z: ot iron :ind copper, :ind continuing the acid trentment while accumulating n prnritntionnl deposition of such flotation. materiel upon the pla*ce-eurt'ncc?l Qi The proce ot lithograining n'ietnlpl:iie. which con in reducing 'the plette-A enrioce in nin leid oath containing in 'licitetion grziritntintr Bunnies composed oil? the i cynnntes iron and copper, and continuing the acid treatment during successive a'infinvitntionel re-depositions of such ilotm tion material. Y

35. The procese of litho-graining metalplete@ which concists in reducing the plateenrfnce in an acid hath containing in flotation gfrnjvitnting granules composed of the c ivfanntes of iron and copper und having the copper-cyenete in 'excess of the iron-cyannte, :ind continuing,y the acid treatment AWhile accumulating :i gravitational deposition ci' .such otation material ,upon the plate-surface.

2th The process of litho-graining metalplntes, which consists .in reducing the platesurface in an acid bath containing in flotation grnvitnting granules composed of the copper-crimine in excess of the iron-cyannte, i :ind continuing the acid treatment during successive gravitational, redepositionsJ or' such flotation material.

271 The process of litho-graining metalplntes oi' Zinc, which consists in reducing the plate-surface in :in acid bath containin in ilotition gmvtating granules compose of salts of two metals other than the metal of the plete sind one of which is iron, and continuing the acid treatment while accumulating :i gravitational deposition of such flotation material upon the plate-surface.

The process of litho-graining metalplates of zinc, `which consists in reducing the plate-surface in an acid bath containing in iotation grnvitnting ranules composed oi' stilts of two metals ct er than the metal of the plate and one of which is iron, and continuing the acid treatment during suc cessive re--depositions of such {iotation material.

2Q., The process of litho-grainng metalpletes oif; zinc, which consists in reducing .in flotation grnvitating granules comp of cyanntes of two metals other than the motel of the plate rind one of which is iron` vnl continuing the acid treatment while acclnnnluting n gravitational deposition of finch `liotzition material upon the plate-surfn el E50. The herein described process of litho gi'nining metnlplntes of zine, which consists in reducing the plate-surfnce in an acid heath containing in iiotation gravitating granules composed of cynnate of two metother than the metal of the plate and one ot which is iron, end containingr the -t'd treatment duringy successive gravitational ice-depositions of such flotation materiot ill. The proce-ss ot' litho-grinning metalplates ot zinc, which consists in reducing the plate-citrine" in :in acid hath containing in flotation grnritnting granules composed cyanates of iron and copper and having thev the plnteeurfe ce in :in acid bath containing.

posed of c p lninlity of continuing tile of salts o ion and cop-oer, and continui the ncicl catment while accumuli. @invitational deposition o such le metei'inl upon the plaie-scenico .rliie process ot' litho-,crei i plates oi the plate.-

n zin incid oath ccntainin;

the plete-sniface i flotation granules conipcseil l l of eJ con'ipoond salt vif'liicli coni'oifises iron-cyancgen salt, anfcontlnuthe icio 'treatment o' ile :iccinnnleting gi'zivitntionni cleinosition ot' sncll flotation material upon the plctes face.

3l. The. process of litho-gremio@ metl ic., which consists in reducing lace in en acid 'oath containL i in fiom;` .n 'tilting' granules composed of a componncl salt 'which comprises iron--cynnogen seit and :i copper-omringen salt, and continu 1o; the aci@ treatment., dining successive nef-depositions of sucif tion nmieiisl;

35..;,'lie process of litho-@inning inentipletes ol zinc, which consists in reduci; j the plate-sofinco in an zicicl oath containir in. tiotation' grzuintingg granules copos-e of n, plnsiiitj? of salts which coi i leest one cyannte of a metal, and coi'finn 'the acid trestrnent i; gimitetionai fieposition of sncn .tiotauon mateial upon the piste-sofinco.

The herein desciiineci pro of itlicgifiining metal-nietes o zincq Wulnc con- .Lalsts in reducing tine pmtesmincc in scid beth co'ziteining inmtation ginnnle" one cjyztnate metal,

solo. trentment filming ositions of .sn-.JiL ilotition. in

terial.

3T. The p'ocess of lithogmmm metsl etes ot xine. which con ts in initial y ng the plntosmfnce in a cli, ite nitric if bath contnining in flotation' iz niposefl of e. ind nie- :nii a one oi: these salts a c vf tot?. :1t/.mi then urtlier 'foi'mingthe gi-nin. ol continu-A in@ 'the acid treatment, dwing successive iei-iepcs'tions oi?. suoli 'iotntion nieu ini.

,E A ss oi inno-giu c. .i having a o Wi coi gi'svitating gienuies conico two 'iiiei'ent metals of non -i metal having inthe lcixl g electro-osmotic' theo acid trezxtnaient .accumulating a gravisnch Yflotation Knete surface.

iotic inteoe. which consists in :reducing uzfnce in acid. bath containing n -grevitsting gfzinulcs composed two di ieient. metals of which one .nt metcl having in the acid bath relativer negative electro-osmotic value,- L. l.ning ttie acid treatment duzing gravit. icnai fsf-depositions of Ms O such notntion material upon the pletesur? 4:1). .)iocess of litlio-graining meta1- plate of zinc7 which consists in reducing the plate Hiace 'in an scid bath containn. notation gruvitutmg granules com# L n compound o metallic salts which v inetelcyenogen salts 'of cyannte o a divalent metal @atm-osmotic value rela-tiviiy hc bath to the Zinc and also the other metnl-cyanogen salt,

incisi of essikrely sccnxnulating'a guvitational .tion of such flotation material upon. platc-snifsce.

.e process o'f litho-graiing zinc fletes of zince 'liicli consists in reducposed. of n compound of metallic salts Winch comprises two metal-cyanogen salts oi' which one the cyenat'e of a divnlent,4 i heffing; s i .lcctio-csmotlc Value relatively .liegst toe. *oath to the Zmc and is also to the metal o" the other inetalcyzmoigen salt, and continuing the acid treatment der successive gravitational 're-depositi` is osnc'n flotation material.

7:33. The process ot' litho-graining nietalplates oi'. Zim, which consists in reducing the plate-.surface in an acid. bat-h containing in flotation ginvitating grannies comp i snl'ismnce which comprises the cy having an elect'oosmotic negative relatively to the unl continuing tnc' uci. treatment wlne nccninc n depositlon of such f tion muteicl upon the plate-surface.

. The piocess of litho-gaining metalpletes of zinc7 which consistsin reducing the plate-surface `1n :in acid bath containing 1n Hoi, gravitnlng granules coimpfosedy of t?. continuing the acid treatment While.'

i tively to that et the gaine, and continuing `the acid treatment during successive re- The herein described process of lithou graining. inetal-ilatcs el zinc, which consists in retira-ing the plate-surface in an acid hath containing in flotation granules com-- posed of a compound of metallic salts7 which comprises the cyanates of two metals other than zinc and having, resliectively, relatively negative and positive electro osmotic values, and one of these having its 3 said value negative relatively to that ofI the l zinc,'a1id continuing the acid treatment while accumulating a gravitational deposition of such iiptation material upon the platesurface.

45. The process of litho-grai ing metal plates of zine, which consists in reducing the plate-surface in an acid bath containing in flotation granules composed of a `com^ pound of metallic salts, which comprises the cyanates of two metals other than Zinc and having, respectively, relatively negative and positive electro-osmotic values, and one of these having its said value negative reladepositions oi such iiotation material upon the plate-surface. l

4G. That improvement in the art ot li tl1o graining metalqilates ot zinc, which consiste in subjecting the plate-surface in an acid bath to a primary reduction initially distributed over the whole surface and then' grmlually restricting that Idistrilmtioni and the regularity of that reduction by a pro-- gressive gravitational deposition of an acid- I r the reduced plate-surface; and then subjecting the .surface to a third reduction by again repeating' the said cperation ou the .sccAv ondarily-reduced plate--stii.`ace, whereby the final surface is obtained by three successive reductions, each of which begins with the plate-surface at a ditl'erent stage of grainformation;

47. That improvementl in the art of lithograining metal'plates of eine, which consists in subjecting the plate surface in an acid bath to a primary reduction initially distributed over they whole Surface and then gradually restricting that distribution and the regularity of that reduction by a pro gressive gravitational deposition of an acidresistant flotation-material; next subjecting the surface to a secnnd reduction by repeating the said, o )eration on the prii'narilys reduced plate-sur ace; and then subjecting the surface to a plurality'of further reductions by successively repeating the said operation on the partially-reduced plate surface, whereby the final surface is obtained by at least tour successive reductions, each of which bevins with. the plate-surface at a different, stage of grainfitormation.

FREDERICK NIEMEYER.

Witnesses H. D. Penney, JOHN Mounts. 

